With reference to FIG. 3, a conventional porous device 200 merely comprises a porous structure 210, and a fluid pressure system (not shown in Figure) is utilized for transmitting high pressure fluid to the porous device 200 and bearing a heavy workpiece (not shown in Figure) by feature of restriction effect. However, the porous structure 210 is limited by its original material characteristics so that the diameter and arrangements for the porous structure 210 is uncontrollable, which may lead the flow rate of the porous structure 210 and the surface flow field of the porous device 200 to be unable to control as well. Therefore, the application field of the porous device 200 is limited substantially.